Milk can and method of forming same



Aug.25,1931. MFAHLMAN 1,820,733

MILK GAN AND METHOD OF FORMING SAME Filed Oct. 29. 1928 ATTORNEYS patented Aug. 25, 193i UNITED STATES PATENT OFFICE DUNCAN J. FAHLMAN, OF DETROIT, MICHIGAN, ASSIGNOR TO BUHL STAMPING COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN MILK CAN AND METHOD F FORMING SAME Application filed October 29, i928. Serial No. 315,875.

The invention relates to the manufacture of cans and more partlcularly milk cans of that type comprising a cyl1ndr1eal body and a flanged bottom telescopically engaged therej 5 with. It is usual to manufacture and assemble these parts in the black metal and subsequent-ly to subject them to the tinning process. lt has been found, however, that in the fluxing operation preparatory to tinning a certain quantity of the acid or flux will penetrate. between the cylinder body and flange and will remain permanently. It has also been found impossible to cause the tin or solder to run between the surface of the body and the flange so that sealing is affected only by the inner coating. As a consequence, cans so constructed frequently bccome leaky and the acid or flux remaining in the joint will work its way inward into the can, contaminating its contents.

Another difficulty in the manufacture of cans, particularly those designed for use as milk cans, is to avoid the formation of a crevice between thefbottom and the sides in which dirt may lodge. This crevice is due to the fact that in bending the flange the corner will be curved and therebyr form a tapering annular recess. Attempts have been made to cure this defect by the use of an insert between the body and the flange, said insert being fashioned to fill out this tapering space and to leave an unbroken surface. However, such constructions are also defective, particularly in that the flux will pene- 5 trate and remain in the joints having the results above described.

The object of the present invention is to avoid these defects, first, by the production of a can in which the surface of both the cylindrical body and the flange are tinned and sweated together. Second, by so constructing the flanged bottom as to avoid the eurve at the bend and consequently to eliminate the recess. With these objects in view the invention consists of the construction yas hereinafter set forth.

In the drawings:

Figure 1 is a longitudinal section through the lower portion of the can showing the flanged bottom and the joint -between the same and the cylindrical body;

Figures 2 and 3 are sections illustrating the successive steps in forming the flanged bottom to avoid thc curve;

Figure 4 is a View illustrating the step of tinningthe portion of the cylindrical body which is to be engaged by the flanged bottom;

Figure 5 illustrates the manner of engago0 ing the tinned body with the bottom.

As shown, A represents the cylindrical body of a can, B the bottom member which is of the usual concave form and is provided with a depending cylindrical flange C for telescopically engaging the cylindrical body. To eliminate the curved corner between the bottom and its depending flange, l proceed as follows The bottom is first pressed to form the flange C with a curve portion D intermediate the same and the bottom B, said curved portion projecting outward beyond the outer surface of the flange as illustrated in Figure 2. 'lhe bottom is then engaged with dies E and F, the former fitting the curved bottom surface and the latter surrounding the cylindrical surface of the flange C. 'lhe die member F is then moved toward the die member E and in so doing irons down the curve l) deflecting the same axially upward and producing a sharp angle corner as indicated at G, Figure 3.

After separately forming the bottom and the cylindrical body, the bottom is tinned by immersion in a tinning bath after fluxing, 35 thereby coating the entire surface including that of the flange C. The cylindrical body A is then filmed at its lower portion by immersion in a tinning bath as indicated in Figure 4. This operation not only coats* the 9 surface with the tin but also by heating the body expands the diameter thereof so as to give eas clearance for the insertion of the tinned anged bottom. The parts are then quckl assembled by vpressing the hot body over t ie cool bottom and as soon as the temperature in the two vparts e( ualizes this will form a shrink fit. If desire the flange may be mechanically locked to the body by one or more indcntations as indicated at H, after which the combined structure is subjected to the regular tinning operation which coats all of the exposed surfaces. At the same time this tinning operation by heating up the joint bef-)veen the body and bottom flange will sweat these parts together forming a perfect seal. As the bottom has the sharp angle corner G there will be no crevice left for the accumulation of dirt and the tinnin(Y operation will make a slnooth and unbro {en -surface.

What I claim as my invention is:

1. In the manufacture of cans having a cylindrical body and a bottom provided with a cylindrical flange fitting within said body, the steps of first forming the bottom and the flange with a connecting annular portion rounding radially outward beyond the 011tside diameter of the flange and of then compressing said annular rounding portion radially inward thereby deflecting the same axially upward to fill up the corner between said bottom and body. l

2. In the manufacture of cans having a cylindrical bodyand a bottom provided with a dependin cylindrical flange fitting within said bod t ie steps of first tinning the bottom and its ange, then tinning the portion of the body which is to engage said flange and while still hot engaging said body with the flange and finally sweating the joint between said body and can to seal the same.

3. In the manufacture of cans having a cylindrical body and a bottom with a depending cylindrical flange fitting within said body, `the ste s of first tinning the bottom then tinning t e portion of the cylindrical body which engages the cylindrical -flange and while still hot engaging said body with the flange and then tinning the entire body and` then tinning the entire. body and simultaneusly sweating the joint between the body and ange. v y

5. Acan comprising a cylindrical body, a bottom having a dependin cylindrical flange and an integral axially de ected portion complctely filling out the corner to avoid a crevice between said bottom and the cylindrical bod y said flange and body being sweat soldered and shrunk the one upon the other.l In testimony whereof I affix my signature.

DUNCAN J. FAHLMAN.

simultaneously sweating the joint between said body and flan e.

4. In the manu acture of cans having a cylindrical body and a bottom provided with a depending cylindrical flange fitting within said flange, the steps of first forming said bottom and flange with a connecting annular portion rounded radially outward beyond the outer diameter of the flange and then pressing said rounded annular portion radially inward and upward to fill out the corner, tinning the bottom and flange, tinning the portion of the body which is to engage the flange and while hot pressing the same into engagement with the flange to form a shrink fit and 

